1. Field of the Invention
The present invention relates to a converter for satellite communication reception for receiving mutually orthogonal linear polarized waves, and more particularly to the structure of the input parts of waveguides.
2. Description of the Related Art
Usually, where linear polarized waves of up to about 12 GHz in the frequency range of input signals are to be received by a converter for satellite communication reception of this kind, a pair of probes are arranged in mutually orthogonal directions within a waveguide, and a vertically polarized wave is coupled to one of the probes while a horizontally polarized wave is coupled to the other probe.
However, where the frequency range of input signals is as high as 20 GHz for instance, the problem of interference between the vertically polarized wave and the horizontally polarized wave becomes significant in the constitution described above. Therefore, where linear polarized waves of an extremely high frequency range are to be received, the inside of the waveguide is branched into two paths, one for the vertically polarized wave and the other for the horizontally polarized wave, and polarized signals detected by probes are prevented from interfering with each other by coupling the vertically polarized wave and the horizontally polarized wave to the probes in their respective propagation paths.
However, where the vertically polarized wave and the horizontally polarized wave are to be coupled to probes in two separate propagation paths as according to the prior art described above, usually each one of the two probes is fitted to a separate circuit substrate, one circuit substrate being provided with a signal synthesizing means, and signals are transmitted from the other circuit substrate to the circuit substrate provided with the synthesizing means via a connecting section, because the electric field directions of the vertically polarized wave component and the horizontally polarized wave component are orthogonal to each other in the propagation paths. However, synthesis of signals detected by two probes using two circuit substrates not only makes the pattern and structure more complex but also involves the problems of increased signal losses and it is impossible to reduce the interference sufficiently and, moreover, complicates the circuit substrate ability to work on account of the high frequency of the polarized signals.
There is also proposed an alternative according to which both probes are fitted to the same circuit substrate and an adapter is provided in between this circuit substrate and the waveguide, which aligns the electric field directions of the vertically polarized wave component and the horizontally polarized wave component into the same direction, but such an adapter would complicate the structure and accordingly this adapter would boost the cost of the structure.
In view of the problems involved in the prior art, the present invention provides a simply structured converter for satellite communication reception which can contribute to reducing signal losses and simplifying the assembly work.
In order to achieve the above-stated object, a converter for satellite communication reception according to the invention is provided with a case having two waveguides in which linear polarized waves orthogonal to each other propagate, a circuit substrate fitted to this case and two probes disposed on this circuit substrate, wherein these two probes are arranged in the waveguides.
This configuration, as the mutually orthogonal linear polarized waves are coupled to their respective probes in the two waveguides of the case and signals detected by these probes can be amplified and synthesized on the same circuit substrate, not only can signal losses and interference be reduced but also the structure of the input parts of the waveguides can be simplified.
If, in the configuration described above, the two probes are composed of pin members and these pin members are supported by the circuit substrate by soldering or otherwise, the mutually orthogonal linear polarized waves can be securely coupled to the pin members within the respective waveguides. In this case, if both pin members are formed in an L shape and a ground pattern provided on the circuit substrate is utilized as a reflective face for these pin members, the structure can be simplified even more.
Or, in the configuration described above, it is also possible to compose the two probes of electroconductive patterns provided on the circuit substrate and fit a short cap as a reflective face for these electroconductive patterns to the circuit substrate, and in this way it is also possible to securely couple the mutually orthogonal linear polarized waves to the electroconductive patterns within the respective waveguides.